Particles emitted from radioisotopes can be used to convert the radiant energy into electricity. Radioisotope energy conversion for power generation has been intensively studied to develop power sources for a wide range of applications from energizing cardiac pacemakers in the human body, to challenging outer planet missions. As compared to various indirect conversion methods collecting the electricity from the secondary energy forms of heat or light generated by radiation, direct conversion methods produce electric power directly from energetic particles. Beta particles can produce electron-hole pairs in semiconductors via their loss of kinetic energy and can contribute to the generation of electric power. Although potential applicability of radioisotopes in portable power sources that do not require recharging seems very attractive, it has been reported that only a small portion of the whole radiation energy can be converted into electrical energy. Moreover, most betavoltaic cells suffer from serious radiation damage to the lattice structures of semiconductors and subsequent performance degradation due to the high kinetic energy of the beta particles. Alternatively, to minimize lattice damage in semiconductors, wide band gap materials are typically used. However, radiation-resistive materials, such as SiC and GaN, still show very low energy conversion efficiencies. Very little improvements have been made even after vigorous research on various improvement methods utilizing porous structures, inverted pyramidal cavities, and three dimensional silicon pillar structures to increase rectifying junction areas. In view of the foregoing, a need still exists for a more efficient method and device for producing electrical power from radiation.